Eight items were empirically derived from an extensive review of the literature and a review of case histories from previous studies conducted by this laboratory on the subject of the schizophrenia spectrum. A questionnaire named "The Symptom Schedule for the Diagnosis of Borderline Schizophrenia" was applied to 31 case histories (14 diagnosed borderline schizophrenia and 17 outside the spectrum). The Schedule reliably differentiated between the two groups.